Original Article
Abstract
Excessive cutting depth during leveling of agricultural land increases power needed by the tractor drawbar and will result in undesirable slippage and excessive strain on the tractor engine. The result of sustained excess will be the break-down of the tractor. An auxiliary blade depth controller ...
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Excessive cutting depth during leveling of agricultural land increases power needed by the tractor drawbar and will result in undesirable slippage and excessive strain on the tractor engine. The result of sustained excess will be the break-down of the tractor. An auxiliary blade depth controller to prevent overloading during leveling was designed, fabricated and evaluated in this study. The system consists of a closed loop that obtains the real tractor engine speed using a dynamo and compares the critical and desired speeds of the engine as controlled by the user by means of a manual keyboard. The data is recorded in the main microcontroller memory and displayed online on a LCD. The system governing the blade depth prevents attainment of critical engine speed that will cause overloading. The depth controller system overrides manual control and sends pulses to the solenoid valve to adjust the blade depth cylinder to decrease the depth of excavation until the desired engine speed is attained. After eliminating the risk of overload, the system switches blade command back to the laser control box. The system was evaluated on a laser-guided land leveler on farmland. Fuel consumption and field performance of the machine were determined with and without use of the proposed control system. The test was carried out using a t-test with five replications. The result demonstrated a significant difference at 5% probability for use of the proposed system (p < 0.05). The new system decreased fuel consumption 18.4% and increased field performance 19.7%, which makes it an effective cost-saving measure.
Original Article
Abstract
Variations in lighting are a problem for visual systems. In the current research, a new thresholding method using a 3D Euclidian elliptical surface was defined and applied for plant detection purposes. The results showed that this method had lower type I error, type II error, total error and mean square ...
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Variations in lighting are a problem for visual systems. In the current research, a new thresholding method using a 3D Euclidian elliptical surface was defined and applied for plant detection purposes. The results showed that this method had lower type I error, type II error, total error and mean square error compared with those of conventional segmentation methods. The method was evaluated for detection of cabbage and lettuce from images. The results showed the proposed method located cabbages in the images with 85.26% accuracy. When the proposed method was combined with image-based shape features it identified lettuce from the images at 66.67% accuracy.
Original Article
Abstract
This study investigated the effect of different concentrations of nanocrystalline cellulose (NCC) on the physical properties of starch-NCC nanocomposites. The nanoparticle distribution in the polymer matrix was investigated using x-ray diffraction. The heat resistance and mechanical properties of the ...
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This study investigated the effect of different concentrations of nanocrystalline cellulose (NCC) on the physical properties of starch-NCC nanocomposites. The nanoparticle distribution in the polymer matrix was investigated using x-ray diffraction. The heat resistance and mechanical properties of the film were measured by differential scanning calorimetry and tensile testing. Investigation of nanocomposite properties showed that the addition of NCC to starch film increased the moisture resistance of the film. With the addition of up to 9% NCC, the ultimate tensile strength of the nanocomposite samples increased from 5.9 to 7.64 MPa and the strain-to-break decreased from 34.82% to 20.66%. This trend was not significant for nanocomposite samples containing high concentrations of NCC (5%, 7%, 9%) because of their crystalline nature, the unique mechanical properties of the cellulose and the establishment of hydrogen bonds between the starch and cellulose nanoparticles. Investigation of thermal resistance of the nanocomposite samples showed that the addition of up to 9% NCC increased the melting point of the film from 218 to 251.5 °C. Increasing the NCC concentration decreased the glass transition temperature of the nanocomposite samples. The results show that the performance of the NCC differed in the amorphous and crystalline regions of the starch.
Original Article
Abstract
Gum is used to stabilize mayonnaise emulsion in industry. The present study investigated the effect of carboxymethyl cellulose (CMC) with gum tragacanth (T) on the physicochemical and sensory properties of mayonnaise after 1 and 30 d of storage. T contents from zero (control) to 100% in the CMC was used ...
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Gum is used to stabilize mayonnaise emulsion in industry. The present study investigated the effect of carboxymethyl cellulose (CMC) with gum tragacanth (T) on the physicochemical and sensory properties of mayonnaise after 1 and 30 d of storage. T contents from zero (control) to 100% in the CMC was used to produce mayonnaise. The results of rheology were analyzed using the Herschel-Bulkley model which indicated that all samples showed pseudoplastic behavior and exhibited weak gel-like behavior in the studied frequency range. The stability of the samples increased as the content of T increased to ≥50% after 30 d of storage. Results from color measurement showed that use of T at most concentrations decreased the L* and increased the a* and b* of the samples. The microstructural images and sensory evaluation showed no significant difference from the control over both periods of storage. The results of this study indicate that ≥50% T increased water binding capacity, stability, continuous phase viscosity, and rheological behavior and produced acceptable sensory scores confirming that it is appropriate for replacement of a percentage of CMC in the mayonnaise samples.
Original Article
Abstract
Bacillus subtilis K40b was isolated from rice rhizospheres and its potential for production of xylanase was evaluated using biochemical methods. The gene for xylanase in B. subtilis K40b was amplified, sequenced and assigned to the NCBI Genebank. The gene size was estimated to be 563 bp encoding 413 ...
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Bacillus subtilis K40b was isolated from rice rhizospheres and its potential for production of xylanase was evaluated using biochemical methods. The gene for xylanase in B. subtilis K40b was amplified, sequenced and assigned to the NCBI Genebank. The gene size was estimated to be 563 bp encoding 413 amino acids. Comparison of the xylanase gene with reference sequences showed that the xylanase of B. subtilis k40b belongs to the glycosyl hydrolyase family 11 (GH11) and was closely related to Bacillus xylanase. Response surface methodology using a central composite design was applied to determine the optimum temperature and pH of the xylanase B. subtilis K40b catalytic activity. Testing was carried out at temperatures of 25 to 75 °C and pH values of 4.5 to 8.5. ANOVA was used to derive a quadratic model equation for prediction of enzyme activity. Results showed that the optimal conditions for xylanase activity were 6.5 pH and 50°C. Alkaline pH and temperatures >70°C and <50°C resulted in a noticeable decrease in xylanase activity.
Original Article
Abstract
Recent drought has increased the consumption of fresh water resources to peak values in most parts of Iran. Water resources managers and planners have been forced to consider the use of all conventional and marginal-quality water (water of low quality) sources during planning. One of these marginal sources ...
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Recent drought has increased the consumption of fresh water resources to peak values in most parts of Iran. Water resources managers and planners have been forced to consider the use of all conventional and marginal-quality water (water of low quality) sources during planning. One of these marginal sources is treated municipal wastewater. The present study investigated the effects of the use of a drip irrigation system dispersing municipally-treated wastewater from the city of Shiraz on the chemical characteristics of clay loam soil in Badjgah in Fars province. Six water quality parameters were examined for treatments using freshwater, treated wastewater and fertilizer to irrigate broccoli. The results showed that application of treated municipal wastewater significantly increased the pH, SAR, and OC of the soil over that of the other treatments at 5% probability. Concentration of most chemical elements, such as nitrogen, potassium, and magnesium, and heavy metals, such as zinc, iron and lead, increased significantly increased at 5% probability for the wastewater treatment over the values for the other treatments.
Original Article
Abstract
Concrete is the most common material used to line irrigation canals and must maintain its durability for the lifetime of the canal. Compressive strength has been used as an index to control the quality of concrete; concrete that remains durable under freeze-thaw conditions is that with high compressive ...
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Concrete is the most common material used to line irrigation canals and must maintain its durability for the lifetime of the canal. Compressive strength has been used as an index to control the quality of concrete; concrete that remains durable under freeze-thaw conditions is that with high compressive strength. Research has shown that concrete linings can show suitable compressive strength in the first days of existence, but begin to decompose after a period and lose the property of durability. The present study examined the relationship between compressive strength and the durability parameters of initial water absorption, final water absorption, water penetration depth and porosity in the Variyaneh and Dingel-e Kahriz irrigation canals in the province of Hamedan. Laboratory testing was carried out on 27 cores (69 mm in diameter; different lengths) extracted from the concrete linings of canals. The cores were prepared and their compressive strength and durability parameters were determined. The results show an inverse linear relationship between the compressive strength and density of the samples and their porosity. The durability parameters of initial water absorption, final water absorption, and water penetration depth showed no significant relationship. The results indicate that compressive strength is not sufficient for evaluation of the durability of concrete lining. Of the 27 cores, 40% had acceptable compressive strength. Of these, 50% showed acceptable durability parameters for exposure to freeze-thaw. The results also showed that the mean penetration depth and porosity of the samples were >2.5 times greater than the maximum recommended values and that the initial and total water absorption values were >1.5 times greater than the maximum recommended values. It is evident that the concrete linings will decompose more quickly than the anticipated lifetime from the influence of water and other expansive solute solutions in cold weather. It was noted that samples having similar compressive strengths had durability parameters that were greater or less than acceptable values. These results suggest that the compressive strength of concrete alone is insufficient to ensure durability and it is necessary to examine additional parameters affecting the lifetime of the concrete linings.
Original Article
Abstract
Different additives have been considered to improve stabilization of the engineering properties of fine-grained soil. The present study investigated the effect of the addition of sewage sludge ash on the compressive strength of clay soil at optimum moisture content and under saturated conditions. The ...
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Different additives have been considered to improve stabilization of the engineering properties of fine-grained soil. The present study investigated the effect of the addition of sewage sludge ash on the compressive strength of clay soil at optimum moisture content and under saturated conditions. The four treatments tested were the addition of 0%, 5%, 10% and 15% sewage sludge ash to clayey soil. The compaction characteristics of the treatments were determined using a Harvard compaction test. Then 24 specimens from each treatment were prepared at curing times of 7, 14, 28 and 90 days. Testing included three replications for a total of 96 specimens created using a Harvard compaction mold. The specimens were subjected to unconfined compressive strength tests. The results showed that increasing the sewage sludge ash content of the soil decreased the maximum dry unit weight and increased the optimum moisture content. The compressive strength of the soil treated with sewage sludge ash increased for both the optimum moisture and saturated conditions. It was found that the compressive strength of the treated soil significantly increased as the curing time increased.
